diff --git a/src/app/service-graph/services/graph.store.ts b/src/app/service-graph/services/graph.store.ts
index cf438e6..0dd6653 100644
--- a/src/app/service-graph/services/graph.store.ts
+++ b/src/app/service-graph/services/graph.store.ts
@@ -195,6 +195,7 @@
   // graph operations
   private addNode(node: IXosBaseModel) {
     const nodeId = this.getNodeId(node);
+
     this.serviceGraph.setNode(nodeId, node);
 
     const nodeType = this.getModelType(node);
@@ -261,10 +262,33 @@
 
   // helpers
   private getModelType(node: IXosBaseModel): string {
+    if (!node) {
+      this.$log.warn(`[XosGraphStore] Someone called getModelType with an empty model: ${node}`);
+      return 'missing-node';
+    }
+
     if (node.type) {
       // NOTE handling "ownership" links
       return node.type;
     }
+
+    if (node.class_names.indexOf('ServiceInstance,') > -1 ) {
+      return 'serviceinstance';
+    }
+
+    if (node.class_names.indexOf('Service,') > -1 ) {
+      return 'service';
+    }
+
+    if (node.class_names.indexOf('Instance,') > -1 ) {
+      return 'instance';
+    }
+
+    if (node.class_names.indexOf('Network,') > -1 ) {
+      return 'network';
+    }
+
+    this.$log.warn(`[XosGraphStore] Unkown model type: ${node.class_names}`);
     return node.class_names.split(',')[0].toLowerCase();
   }
 
@@ -287,6 +311,7 @@
   private getNodeId(node: IXosBaseModel): string {
 
     const nodeType = this.getModelType(node);
+
     switch (nodeType) {
       case 'service':
         return this.getServiceId(node.id);
diff --git a/src/app/service-graph/services/node-positioner.service.ts b/src/app/service-graph/services/node-positioner.service.ts
index 17823b7..bfe6c58 100644
--- a/src/app/service-graph/services/node-positioner.service.ts
+++ b/src/app/service-graph/services/node-positioner.service.ts
@@ -73,15 +73,15 @@
           return all;
         }, {});
 
-        // find the nodes that don't have a position defined and put them at the top
-        const allNodes = _.reduce(nodes, (all: string[], n: IXosSgNode) => {
+        // find the nodes that don't have a position defined and put them at the bottom
+        const allServiceNodes = _.reduce(nodes, (all: string[], n: IXosSgNode) => {
           if (n.type === 'service') {
             all.push(n.data.name);
           }
           return all;
         }, []);
         const positionedNodes = Object.keys(positionConstraints);
-        const unpositionedNodes = _.difference(allNodes, positionedNodes);
+        const unpositionedNodes = _.difference(allServiceNodes, positionedNodes);
 
         _.forEach(unpositionedNodes, (node: string, i: number) => {
           const hStep = this.getHorizontalStep(svg.width, unpositionedNodes);